Tetrachloronickelate

A tetrahedral tetrachloronickelate complex ion

Tetrachloronickelates are a class of chemical compounds containing anions consisting of a nickel atom surrounded by four chloride ions. [NiCl4]2−

room temperature tetrachloronickelate complex in water

When concentrated lithium chloride and nickel chloride solution in water is mixed, only a pentaaquachloro complex is formed: [Ni(H2O)5Cl]+. However in other organic solvents, or molten salts the tetrachloronickelate ion can form. Nickel can be separated from such a solution in water or methanol, by partitioning it into a cyclohexane solution of amines.[1]

Substituted ammonia tetrachloronickelates can be thermochromic. At room temperature they can be in a polymeric yellow coloured form, but when heated become bright blue, as the form changes to a tetrahedral arrangement of chlorine around the nickel atom.[2] Yet other amine salts of tetrachloronickelate, such as [(NC3H7)3NH]2NiCl4, are blue liquids at room temperature.[2] The trimethylammonium and diethylammonium salts have thermochromic temperatures at 70 °C. The corresponding tetrabromonickelates are also thermochromic with a transition at lower temperatures.[2]

Some tetrachloronickelates can be ionic liquids at room temperature.

History

The blue colour due to the tetrachloronickelate ion was first observed in 1944 when Remy and Meyer melted cesium chloride and cesium nickel trichloride together.[3]


Compounds

formula name Ni Ox structure Remarks references
Cs2NiCl4 cesium tetrachloronickelate 2 blue stable only over 70° [3]
[(CH3)4N]2NiCl4 Tetramethylammonium tetrachloronickelate dark blue [4]
[(C2H5)4N]2NiCl4 Tetraethylammonium tetrachloronickelate 2 [5][3]
[H2NN(CH3)3]2NiCl4 1,1,1-trimethylhydrazinium tetrachloronickelate 2 blue, only stable over 145°C, under this is yellow [6]
[(C6H5)4As]2NiCl4 bis-tetraphenylarsonium tetrachloronickelate blue melts 199.5° [4]
[(C6H5)3CH3As]2NiCl4 bis-triphenylmethylarsonium tetrachloronickelate blue [3]
[C2mim]2NiCl4 1-ethyl-3-methylimidazolium tetrachloronickelate(II) 2 tetragonal I41/a a=14.112 c=19.436 V=3871.1 Z=8 density=1.47 MW=422.84 melt 92° [7][8]
[C4mim]2NiCl4 1-butyl-3-methylimidazolium tetrachloronickelate(II) 2 dark blue melt 56° [7]
[C5mim]2NiCl4 1-pentyl-3-methylimidazolium tetrachloronickelate(II) 2 dark blue liquid [7]
[C6mim]2NiCl4 1-hexyl-3-methylimidazolium tetrachloronickelate(II) 2 dark blue liquid [7]
[C7mim]2NiCl4 1-heptyl-3-methylimidazolium tetrachloronickelate(II) 2 dark blue liquid [7]
[C8mim]2NiCl4 1-octyl-3-methylimidazolium tetrachloronickelate(II) 2 dark blue liquid [7]
[NH3CH2CH2NH3]NiCl4 ethylenediammonium tetrachloronickelate(II) 2 perovskite layered, space group P21/c a=8.441, b=6.995, c=6.943, β=92.925 Z=2 brown, isostructural with Mn, Cu, Pd, and Cd compounds [9]

Related substances

References

  1. ↑ Florence, T. M.; Farrar, Yvonne J. (July 1968). "Liquid-liquid extraction of nickel with long-chain amines from aqueous and nonaqueous halide media". Analytical Chemistry. 40 (8): 1200–1206. doi:10.1021/ac60264a010.
  2. 1 2 3 Ferraro, John R.; Sheren, Anne T. (3 February 1978). "Some new thermochromic complexes of Nickel(II) of the type [R/sub x/NH/sub 4-x/]2NiCl4". Inorganic Chemistry. 17 (9): 2798–2502. doi:10.1021/ic50187a032.
  3. 1 2 3 4 Gill, Naida S.; Nyholm, R. S. (1959). "802. Complex halides of the transition metals. Part I. Tetrahedral nickel complexes". Journal of the Chemical Society (Resumed): 3997. doi:10.1039/JR9590003997.
  4. 1 2 Cotton, F. A.; Faut, O. D.; Goodgame, D. M. L. (January 1961). "Preparation, Spectra and Electronic Structures of Tetrahedral Nickel(II) Complexes Containing Triphenylphosphine and Halide Ions as Ligands". Journal of the American Chemical Society. 83 (2): 344–351. doi:10.1021/ja01463a021.
  5. ↑ Inman, Guy W.; Hatfield, William E.; Jones, Edwin R. (August 1971). "The magnetic properties of tetraethylammonium tetrachloronickelate(II) and tetraethylammonium tetrabromonickelate(II)". Inorganic and Nuclear Chemistry Letters. 7 (8): 721–723. doi:10.1016/0020-1650(71)80078-8.
  6. ↑ Goedken, V. L.; Vallarino, L. M.; Quagliano, J. V. (December 1971). "Cationic ligands. Coordination of the 1,1,1-trimethylhydrazinium cation to nickel(II)". Inorganic Chemistry. 10 (12): 2682–2685. doi:10.1021/ic50106a011.
  7. 1 2 3 4 5 6 Meredith, M. Brett; McMillen, C. Heather; Goodman, Jonathan T.; Hanusa, Timothy P. (August 2009). "Ambient temperature imidazolium-based ionic liquids with tetrachloronickelate(II) anions". Polyhedron. 28 (12): 2355–2358. doi:10.1016/j.poly.2009.04.037.
  8. ↑ Hitchcock, Peter B.; Seddon, Kenneth R.; Welton, Thomas (1993). "Hydrogen-bond acceptor abilities of tetrachlorometalate(II) complexes in ionic liquids". Journal of the Chemical Society, Dalton Transactions (17): 2639. doi:10.1039/DT9930002639.
  9. ↑ Skaarup, Steen; Berg, Rolf Willestofte (September 1978). "Structural properties and vibrational spectra of the ethylene-diammonium family of perovskite layer-type crystals: [NH3CH2CH2NH3] [MCl4], M = Ni, Pd, Cu, Cd, Mn". Journal of Solid State Chemistry. 26 (1): 59–67. doi:10.1016/0022-4596(78)90133-0.
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